Method and means for creating subterranean excavations and/or constructions

ABSTRACT

A system and method for creating a subterranean construction including an excavation means adapted to excavate a first material from a subterranean position, means for clearing this first material from the excavation site, and means for supplying the void left by the excavation with a supply of a second material that is dissimilar to the first material.

TECHNICAL FIELD

The present invention relates to a means and method for creatingsubterranean excavations and/or constructions. For the purpose of thisspecification, the term construction is intended to include, but not belimited to, piers, retaining walls, piping, ceilings, floors, barriersand filters.

BACKGROUND ART

In this specification unless the contrary is expressly stated, where adocument, act or item of knowledge is referred to or discussed, thisreference or discussion is not to be construed as an admission that thedocument, act or item of knowledge or any combination thereof was at thepriority date, publicly available, known to the public, part of commongeneral knowledge; or known to be relevant to an attempt to solve anyproblem with which this specification is concerned.

When excavating down to a required level for whatever reason, it hashitherto been necessary to excavate the walls of the excavation site atapproximately 45° in order to prevent the earth walls from collapsinginwardly on the excavation site. Only once the desired base level hadbeen reached could work commence on the construction of a structure orconstruction in the excavation.

Methods of shoring the walls of an excavation have been developed whichallow a trench or bore etc with vertical walls to be dug, thus reducingthe size of the excavation and the amount of earth that needs to beexcavated.

Shoring methods have included such techniques as using structuralelements to brace the excavation, and even filling a hole with a slurrywhile the excavation is taking place.

However, these shoring operations can be time consuming and thereforecostly.

It is an object of the present invention therefore to provide a meansand method of creating subterranean excavations and/or constructionsthat substantially ameliorates the aforementioned difficultiesassociated with known excavation techniques, or at-the least, providethe public with a useful alternative.

It is a further object of the invention to provide a means and method ofcreating a subterranean excavation and/or construction that involvesexcavating as little material as possible.

Other objects and advantages of the present invention will becomeapparent from the following description, taken in connection with theaccompanying drawings, wherein, by way of illustration and example, anembodiment of the present Invention is disclosed.

For the purpose of this specification the word “comprising” means“including but not limited to”, and the word ‘comprises’ has acorresponding meaning.

DISCLOSURE OF THE INVENTION

In one form of this invention although this may not necessarily be theonly or Indeed the broadest form of this there is proposed a system forcreating a subterranean construction including an excavation meansadapted to excavate a first material from a subterranean position, meansfor clearing this first material from the excavation site, and means forsupplying the void left by the excavation with a supply of a secondmaterial that is dissimilar to the first material.

In a further form, the invention may be said to reside In a method ofcreating a subterranean construction by excavating and removing a firstmaterial from a subterranean position, and backfilling the void left bythe excavation and removal with a supply of a second material that isdissimilar to the first material.

Preferably, the second material is adapted to form, at least in part,the construction.

Preferably, in an alternative, the second material is a granularmaterial.

Preferably, the subterranean position is a bore, shaft or tunnel.

Preferably, the bore or tunnel is approximately horizontal.

Preferably, the excavation means is adapted to excavate in any desireddirection away from the subterranean position, so that this position isa starting positing for the excavation and construction process.

Preferably, the void left by the excavation is pressurised with thesecond material, and this second material exerts pressure on theexcavation means that drives it in the desired direction.

Preferably, the excavation means is adapted to excavate upward from thefirst subterranean position.

Preferably, in an alternative, the excavation means Is adapted toexcavate downward from the first subterranean position.

Preferably, the excavation means includes at least one digging tooth.

In one form, the or each tooth is supported by means which are driven soas to provide a cutting action.

Preferably, the or each tooth is supported by means which are driven soas to reciprocate.

In one form, said tooth support means is a chain.

In a further form, the chain is continuous, and passes around at least apair of sprockets, at least one of which are driven.

Preferably, the chain is driven by a power source.

This power source may be a hydraulic, electric or internal combustionmotor.

Preferably, the second material is adapted to solidify

Preferably, the second material is a cementious material.

Preferably, the material that is adapted to solidify is a concreteslurry.

Preferably, the means for clearing excavated material does so byentraining this material in a fluid stream.

Preferably, said means creates a flow of the fluid at or neat theexcavation face, for the purpose of entraining excavated material andremoving this from the excavation site.

Preferably, the fluid is air.

Preferably, pumping the second material into the void left byexcavation, forces the excavation means upwardly or in the desireddirection of excavation if this is not upwardly.

In a further form, the invention may be said to reside in a method ofutilising the abovementioned means for creating a subterranean structurecomprising the steps of drilling a pair of vertical bores, drilling ahorizontal bore between the vertical bores, inserting the means forcreating a subterranean structure into the horizontal bore so that itcan then excavate in the desired direction, and backfilling the voidleft by excavation with a second material that is dissimilar to thefirst material.

Preferably, the horizontal bore is sealed at both ends in order toprevent the second material from filling the vertical bores.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of this invention it will now be describedwith respect to an embodiment which shall be described herein with theassistance of drawings wherein;

FIG. 1 is a not to scale, schematic view of the system; and

FIGS. 2 and 3 are cross-sectional views through the horizontal bore inFIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, where there is a pair of substantiallyparallel, vertically spaced apart bores 2, called ‘guide’ bores, havinga horizontal, or ‘excavating’ bore 4 passing between them proximate totheir ends. The horizontal bore 4 is drilled at the required depth i.e.if the construction, which for the purposes of this example is a wall,is to be constructed to a depth of 5 meters below ground level, thehorizontal bore 4 is dug at this depth.

The equipment for forming the subterranean structure is then directeddown into the bores and set up in the following fashion.

A wear strip 6 is passed between the two vertical bores 2 via thehorizontal bore 4, the wear strip 6 being sized and adapted to sealagainst the sides of the horizontal bore 4 along its edges so as tocreate a cavity above the wear plate 6, and one below it.

The wear strip 6 supports a chain 8 on its upper side in guide tracks10, so that the chain 8 be driven with a reciprocating motion withrespect to the wear/seal strip 6. Connected to the chain 8 is aplurality of sets of upwardly directed digging teeth 12, which, when thechain is driven, have a cutting action.

Formed into the underside of the wear strip is a pair of passageways 14with a series of holes 16 passing through the walls thereof along theirrespective lengths. Each end of these passageways 14 is then connectedto a conduit 20 that supplies it a second material, which for thepurposes of this example is concrete, from a source 22 up at groundlevel.

A further conduit is fed down each one of the vertical bores 2 to theend of the horizontal shaft 4 just above the wear plate 6.

In use, concrete is supplied via the conduits 20 to the passageways 14running in the under or sealing side of the wear strip 6, this concretethen passes through the holes 16 in the walls of these passageways andout into the cavity below the wear strip 6. Concrete 19 continues to bepumped into this cavity until sufficient pressure is reached in thislower cavity that the concrete begins to force the wear strip 6 upwardstowards ground level.

As it does this, the chain 8 is being driven so as to reciprocate fromside to side. As the wear strip 6 is forced upwardly by the pressure ofconcrete 19 beneath it, so to are the digger teeth 12 forced upwardly,and these are also reciprocating with a cutting action by virtue oftheir attachment to the chain 8. When these digger teeth 12 come intocontact with the roof of the. horizontal bore 4, they cut away at andexcavate earth, which falls from the ceiling of the bore 4.

One of the pair of further conduits 30 provides a fluid, which for thepurposes of this example is air, at pressure to the cavity above thewear strip 6, and the other conduit 32 provides a source of vacuum.Between them they create air movement along the upper cavity of thehorizontal bore 4 from one end to the other, which is sufficient toentrain the excavated earth therein, and this waste material extractionline 32 draws this earth up to ground surface.

As the concrete 19 cures, it forms a subterranean wall 40 in the groundwithout the need to excavate additional earth beyond that which had tobe displaced in order to allow the wall 40 to be formed in the firstplace.

So long as concrete 19 is continued to be pumped into the cavity belowthe wear strip 6, the wear strip 6, chain 8, digging teeth 12, and theother ancillary equipment associated with these, will continue to bedisplaced upwards by the concrete until the digging teeth 12 breakthrough at ground level.

A curtain seal 42 extends down from the ends of the wear plate 6 so asto prevent the concrete from filling the vertical bores 2. With suchseals, the cement does not need to cure before the wear plate isdisplaced upwardly. In this example we would start at the bottom andpressure on until the desired height has been reached. Leave the ends inuntil material solidifies and then remove chains and seals etc ifnecessary and fill bores. Another solution to this problem however mightbe to pressurise the vertical bores by filling them with the secondmaterial. The wear plate would then need to be extended in length sothat it seals to the edges of the vertical bores 2.

A further solution may be to develop a moving seal (not illustrated) inthe form of a belt running on pulleys or rollers.

In an alternative application, the tunnel providing the startingposition may be dug at a lesser depth, and the teeth directed downwardlyand backfilled with the second material from above, so as to excavate ina downward direction whilst backfilling with the second material.

In yet a further, alternate application, the second material used tobackfill the excavated cavity is a commercially available granularmaterial which attracts mineral oil deposits from the surroundingground. After a period of time, the system can be used to excavate overthe same plane/line and remove the granules. These granules can then becleaned of oils/contaminants and reused for the same purpose. This thenis a useful technique for extracting oil deposits from the ground.

In yet a further, alternate application, the second material used tobackfill the excavated cavity is a granular material such as a finesconcrete or sandy slurry. This then is a useful technique for thecreation and development of underground aquifer's and water holdingfacilities that may be able to regulate ground water.

In yet a further alternative application, the second material as beforementioned in this filtering example can be used under roads andbuildings that have high ground water or salinity issues. This systemcan be used to insert a line of course sand underneath the existinginfrastructure so that the ground water will drain into the porouscorridor of secondary material and drain to a collection point withoutthe demolition of roads and other infrastructure.

It is considered that the means and method for creating subterraneanstructures according to the present Invention would be of particularthose who wish to construct subterranean structures such as piers andretaining walls without having to excavate excess earth.

Although the invention has been herein shown and described in what isconceived to be the most practical and preferred embodiment, it isrecognised that departures can be made within the scope of theinvention, which is not to be limited to the details described hereinbut is to be accorded the full scope of the appended claims so as toembrace any and all equivalent devices and apparatus.

1. An apparatus for creating a subterranean excavation and construction,the apparatus including an excavation means adapted to excavate a firstmaterial from a subterranean position, means for clearing this firstmaterial from the excavation site, means for supplying the void left bythe excavation with a supply of a second material that is dissimilar tothe first material, wherein in use, this second material exerts pressureon the excavation means so as to displace this and drive it in thedirection of excavation, and the means for clearing excavated materialdoes so by entraining this material in a fluid stream.
 2. The apparatusas in claim 1, wherein the subterranean position is a bore, shaft ortunnel, and the apparatus includes means for sealing against a wall orwalls of this bore, shaft or tunnel so as to divide it into two parts,the excavation and clearing means operating in the first part, and theapparatus being adapted to fill the second part with the secondmaterial.
 3. The apparatus as in claim 1, wherein the means for clearingexcavated material creates a fluid stream at or near the excavationface, the stream being strong enough to entrain excavated material andrelocate it.
 4. The apparatus as in claim 3, wherein the fluid stream iscreated by providing fluid at pressure at one end of the bore, shaft ortunnel, and a source of suction at the other end.
 5. The apparatus as inclaim 4, wherein the fluid is a gas.
 6. The apparatus as in claim 4,wherein the fluid is air.
 7. The apparatus as in claim 1, wherein theexcavation means is mechanical in nature.
 8. The apparatus as in claim7, wherein the excavation means includes at least one digging tooth. 9.The apparatus of claim 8, wherein the excavation means includes acontinuous chain of digging teeth.
 10. The apparatus as in claim 9,wherein the continuous chain of digging teeth is driven so as to causethe teeth to act against the first material with a cutting action. 11.The apparatus as in claim 1, wherein the second material is adapted tosolidify, and thereby form, at least in part, the construction.
 12. Theapparatus as in claim 1, wherein the second material is a granularmaterial.
 13. The apparatus as in claim 11, wherein the second materialis a cementitious material.
 14. The apparatus as in claim 13, whereinthe second material is concrete slurry.
 15. An apparatus for creating asubterranean excavation and construction, the apparatus including anexcavation means adapted to excavate a first material from asubterranean bore, shaft or tunnel, means for clearing this firstmaterial from the excavation site, means for supplying void left by theexcavation with a supply of a second material that is dissimilar to thefirst material, sealing means for sealing against a wall or walls of thebore, shaft or tunnel so as to divide it into two parts, the excavationand clearing means operating in the first part, and the apparatus beingadapted to fill the second part with the second material, where thissecond material exerts pressure on the excavation means so as todisplace this and drive it in the direction of excavation, and the meansfor clearing excavated material does so by entraining this material in afluid stream.
 16. A method of creating a subterranean excavation and/orconstruction utilising the apparatus as disclosed in claim 15, whereinthe method includes the steps of excavating and removing a firstmaterial from a subterranean position, and backfilling the void left bythe excavation and removal with a supply of a second material that isdissimilar to the first material.
 17. The method as in claim 16, whereinthe method includes the further steps of drilling a pair spaced apart,substantially vertical bores, drilling a substantially horizontal borebetween the vertical bores, inserting the means for creating asubterranean structure into the horizontal bore and orientating it sothat it can then excavate in the desired direction, and backfilling thevoid left by excavation with a second material that is dissimilar to thefirst material.
 18. The method as in claim 16, wherein the methodincludes the further step of allowing the second material to solidify.19. The method as in claim 15, wherein the method includes the furtherstep of retrieving the apparatus.
 20. (canceled)
 21. (canceled)